Unable to complete a task that was created using `habitica-tasks` without manually calling refresh

[kamni]

When I create a task from within the habitica-tasks interface, I get an error when I try to complete the task, if I don't call a manual refresh. I get the following message:

Wrong tpe argument: stringp, nil

Steps to reproduce:

1. M-x habitica-tasks
2. C-x t n -- enter new task
3. Verify that the task exists on the habitica web site (it does)
4. Move cursor over new task
5. Cx t t
6. Get error message

I notice that the task seems to be missing any :PROPERTIES:.

If I manually refresh the whole page (C-x t g), I don't get the error if I try to complete the task (although it does prompt me for my username and password -- see #20 -- so I'm still unable to complete a task).

Expected behavior: I shouldn't need to manually call refresh when I add new tasks.